The present invention relates broadly to magnetic particle inspection, and in particular to the method of determining the strength and direction of magnetic fields in parts undergoing magnetic particle inspection.
In the prior art, the methods for magnetic particle inspection of ferromagnetic parts have been developed utilizing soft iron indicators and electronic instruments to measure magnetic fields. A major disadvantage in the electronic instrument approach is that holes must be drilled in the part under test for insertion of magnetic field pick-up coils, thus sacrificing at least one part of each configuration and size. The soft iron indicator, when placed on a part during magnetic particle inspection, will indicate the magnetic field necessary to delineate a simulated flaw slit in the indicator. The magnetic field intensity derived in this manner may not have a direct relationship to that necessary to test for a given crack size in a part.